Looks like it was going to display some kind of connection error (netError), but it's hard to tell what is causing it. What is in the address bar for that page?

One possibility is that you've become infected with an add-on or other software that wants to load an advertising tab, but you have security or other software blocking it.

To hunt down a bad add-on, I suggest starting here:

Open the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Take out as much trash as possible here.

Next, in Firefox, open the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

(1) In the left column, click Plugins. If you find a plugin that you don't recognize or which doesn't sound essential, try setting it to "Never Activate". (The most essential Plugin is Shockwave Flash. You can use most sites without the others.)

(2) In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Finally, you can "mop up" remaining issues with the scanning/cleaning tools suggested in this support article: Troubleshoot Firefox issues caused by malware.

Success?

Does it mention a line number (:###) in the error message?

• view-source:chrome://global/content/netError.xhtml

The original block copy and paste included more data such as the line number and had one more line which was the line of code not working. I cannot remember precisely but I believe the line # was 806. I did not save the original error message so if someone could tell me if there is a place where it might be stored I will be happy to retrieve it and post it here.

Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.

• Download the full Firefox installer and save the file to the desktop
  https://www.mozilla.org/en-US/firefox/all.html

If possible uninstall your current Firefox version to cleanup the Windows registry and settings in security software.

• Do NOT remove "personal data" when you uninstall your current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including data in profiles created by other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
• (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

• It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure NOT to remove personal data when you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

If you keep having problems then also create a new profile.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall